99 5.0 Misfires when warmed up

[CDW6212R]

What is involved in changing a harmonic balancer

That's a biggish job, the tight space next to the radiator is potential trouble. Most balancer puller tool kits don't have the proper bolts for the Explorer balancer, so be sure to get the right bolts if you go that route.

I wouldn't suspect the balancer unless there was a noticeable vibration in the engine, or it visually looked bad, or the performance was way off. If the outer ring spins on the inner, the change in timing would directly alter performance, it wouldn't take much movement to notice it. Sometimes the outer ring doesn't move fore or aft at all, just spins a little, and then it's not noticeable. But of course it's hard to see down in there too. I'd skip the balancer while you are hunting the minor miss. Do it if you have another reason to be in there(WP etc), or you have high mileage and are doing maintenance.

 

[1998Exp]

Is it random now? Looked like cyl. 1. If a grounding problem then I would suspect all would get random misfires, except I still don't agree that the coil pack needs any ground through the bracket. Its electrical function is handled by the wiring. It has 3 pins (on each of the two, twin coil packs for an 8 cylinder, or 4 pins for the 3 coil packs for a 6 cyl).

You are correct, in a waste spark system the plug on the exhaust stroke provides the ground for the one that's firing, thus no need for a ground connection on the secondary side.

 

[1998Exp]

What is involved in changing a harmonic balancer

Quite a lot: the space between the radiator and the balancer is very tight, and unless you have a small (but powerful) impact wrench, the radiator has to come out. Although not essential, you will be much better off removing the fan before dealing with the radiator. Get the proper wrenches (slim 36mm and 72mm) for dealing with the fan. You'll also need one of those long arm skinny tools to rotate the tensioner in order to take the belt off. Now you are ready to tackle the radiator. Unfortunately, on the 5.0L, the radiator is sandwiched with the evaporator in an "interesting" way, which prompted some members here to to invent new curse words, but don't let that discourage you, because there is an excellent write-up on this forum how to do that.
Finally you are at the balancer. First order of business is to remove the center bolt, which as I said, is best done with an impact wrench. Some brave souls use the starter to "bump" the crank instead. Next step is to acquire a puller to remove the balancer itself. The primitive ones that auto parts stores sell or rent may do the job, but what you really want is the combined puller/installer, with a bearing.
Some "bake" the balancer in an oven to expand and be easier to install. Don't know how safe that trick is on the bonding material that holds the tone ring, so you are on your own here. Apply some RTV to keyway (to prevent oil from seeping through there), and using the installer (follow the instructions on the box) push in the new balancer, Don't be tempted to skip the installer and just use the center bolt to do the job. It will engage only a couple threads and may damage the crank -- which you definitely don't want. The center bolt needs to be properly torqued, so don't use the impact wrench. You will need a torque wrench and something to hold the crank from turning. Forget strap wrenches - they won't hold even 10% of the required torque. Some stick a large screwdriver in the flex plate, but that's crude. My method is to attach a properly shaped steel bar to the balancer (with bolts that go through two of the three threaded holes) and support it on the frame. Now install the serpentine belt, the radiator, the fan with its shroud, and you are done. I skipped a few details, but that's about it. Easy, right?
By the way, I have a lightly used balancer that I don't need and will give you a good deal on. Be aware that it's heavy, so shipping may be pricey. PM me if you want it.

 

[Turdle]

The 2 long center bolts of the upper intake ( under the 5.0 v8 plaque) work like a charm for pulling the harmonic balancer FYI.

And by removing just the center 2 then replacing them you have done no harm. Just a helpful tip.

Remove the radiator for good access, this way you can also flip the radiator upside down for a good flush.

 

[Sedare]

Quite a lot: the space between the radiator and the balancer is very tight, and unless you have a small (but powerful) impact wrench, the radiator has to come out. Although not essential, you will be much better off removing the fan before dealing with the radiator. Get the proper wrenches (slim 36mm and 72mm) for dealing with the fan. You'll also need one of those long arm skinny tools to rotate the tensioner in order to take the belt off. Now you are ready to tackle the radiator. Unfortunately, on the 5.0L, the radiator is sandwiched with the evaporator in an "interesting" way, which prompted some members here to to invent new curse words, but don't let that discourage you, because there is an excellent write-up on this forum how to do that.
Finally you are at the balancer. First order of business is to remove the center bolt, which as I said, is best done with an impact wrench. Some brave souls use the starter to "bump" the crank instead. Next step is to acquire a puller to remove the balancer itself. The primitive ones that auto parts stores sell or rent may do the job, but what you really want is the combined puller/installer, with a bearing.
Some "bake" the balancer in an oven to expand and be easier to install. Don't know how safe that trick is on the bonding material that holds the tone ring, so you are on your own here. Apply some RTV to keyway (to prevent oil from seeping through there), and using the installer (follow the instructions on the box) push in the new balancer, Don't be tempted to skip the installer and just use the center bolt to do the job. It will engage only a couple threads and may damage the crank -- which you definitely don't want. The center bolt needs to be properly torqued, so don't use the impact wrench. You will need a torque wrench and something to hold the crank from turning. Forget strap wrenches - they won't hold even 10% of the required torque. Some stick a large screwdriver in the flex plate, but that's crude. My method is to attach a properly shaped steel bar to the balancer (with bolts that go through two of the three threaded holes) and support it on the frame. Now install the serpentine belt, the radiator, the fan with its shroud, and you are done. I skipped a few details, but that's about it. Easy, right?
By the way, I have a lightly used balancer that I don't need and will give you a good deal on. Be aware that it's heavy, so shipping may be pricey. PM me if you want it.

Actually it sounds like most of the same disassembly for doing the water pump, which I did 2 years ago when it was -5 F (and ended up replacing the radiator due to nicking the radiator with a screw driver at the same temp. Sucks how brittle they are at that temp LOL) I'm sure I can handle doing that.

 

[Sedare]

Ok update -
New plugs, new IAC, New wires (even the annoying 4th wire), new coil packs.
I checked the codes this morning. Cylinders 5/6/7/8 misfire codes were present, 3 different instances of them, and a fuel too (lean/rich, I cant remember...) I cleared them, and drove for 3 hours. No new CEL, however, I still have my rough idle/misfire issue.

My wife made fun of me for this...

Never once have I WANTED the check engine light to come on in my life more than right now.

 

[Turdle]

Understood. I have a ranger sitting here with sunk valves, which definitely had 2 dead slugs and no codes at all. Frustrating considering another perimeter being slightly off, like the dang DPFE and you can't get the light to turn off. grrr1

weird thing about the misfires on a v8, it seems as long as the spark goes to ground somewhere the cel will not set . I think wires can be mixed up and the PCM would not even care as long as the spark happened ( reached ground)
I've seen with my own eyes a dead cylinder miss caused by a band new spark plug with no cel at all. It took quite a while before we suspected the brand new spark plug.

 

[CDW6212R]

How old is the fuel filter, and the pump/sock, and has any gas been in the truck for a year or more? If the filter age is unknown, remove it and inspect the fuel as you pour it out of the inlet end.

My Mercury developed an issue from bad gas, the tank corroded and fouled(filled) the pump sock. The filter was dirty too, though not very old(5k maybe). That can create a lean condition that the PCM will detect eventually.

 

[crunchie_frog]

No worries, wives are usually right whether they actually are or not. My experience over the years (25+yrs of no shop mechanics troubleshooting my vehicles) is the wires are the most common cause of misfires. Not making good connection at the plug end, bad wires, burnt wires.... Most commonly, for me is the connection on the plug end. I would keep going over that until you are 110% confident this is not an issue. You sound like you have exhausted that route but just letting you know it is a common issue from what I have seen. I guess you have done stuff like spray water or other conductive gas around the wires in the dark when the vehicle is warmed up and looked for sparks. I guess you have tripled checked #1 to #1, #2 to #2, #3 to #3 and so on..... I guess that you have done the conductivity check on the coil packs (even new, replacement ones do not meet specs I have found). I guess you have done a compression test, when warm. I am guessing you have verified you have not cracked the ceramic in the plug installing it, I am guessing you are using either Autolite APP104 or OEM Motorcraft plugs. I am guessing you have verified fuel pressure at the manifold, while warm and running at higher rpms. I am guessing you have cleaned your mass flow air sensor (MAF). I am guessing you may not have done all of these things. One thing that can help, I have found, is to download a scanner recorder/propgram like Forscan, (Forscan is free) You can see graphs and plots and data of while running and you may can see something before the misfire. Again, I go back to the wires, (and plugs, cracked ceramic) as the most likely cause.

For info, CEL has to go through 3 driving cycles before the CEL goes on or off so it does not immediately tell you if the problem is solved. A driving cycle means engine at temperature for x miles/minutes. What I do is start it up, warm it up, drive around the area, shut it off at stop sign, start it up, drive around the area, repeat 2 more times.

"A quitter never wins and a winner never quits."

Let your wife make fun, good therapy for both of you (us).

Good luck!

 

[Sedare]

I have done some, but I will check these start to finish starting again right now.

Edit.
Come to think about it, it makes a slight clicking sound when it misses... Something I discerned back at the start of my issue when cylinder 2 had a dead brand new plug... It made a clicking sound, and knowing how fast I tried to get the plug swap done, I might have cracked the porcelain... But it's terribly inconsistent. I'm going to download that program on my laptop first and setup my obd2 cable drivers, and play with the diagnostics first.

 

[Sedare]

How old is the fuel filter, and the pump/sock, and has any gas been in the truck for a year or more? If the filter age is unknown, remove it and inspect the fuel as you pour it out of the inlet end.

My Mercury developed an issue from bad gas, the tank corroded and fouled(filled) the pump sock. The filter was dirty too, though not very old(5k maybe). That can create a lean condition that the PCM will detect eventually.

I have consistantly driven this for the last 2 years, with no more then 3 days of leaving it parked at any point. Old fuel is not an issue. Filter... maybe.

 

[CDW6212R]

That's good, believe me you want to just change the fuel filter; the tank etc, is a PITA.

I'm pulling my 99 tank because it's not been driven, to replace the pump/screen. I hope the tank is okay, I can use it for my Mercury when I swap to 4WD(and a shorter tank).

I'd replace the fuel filter and confirm fuel pressure(62+ psi), and then go at the plugs and wires again, gently and slowly. I agree plugs are super fragile, as are the wires after a couple of years.

 

[Sedare]

Well I wanted to update this.

My friend of mine took a look at it, and just started over. Pulled wires, pulled plugs, and turns out the glass was cracked on plug 6!

USER ERROR!
I appear to have over tightened it, and broke it. I never did pull the plugs to check them. After replacing this plug, the miss is 100% gone.

However I still have a passive loss of power under very heavy load, but this might actually be tracable to the fuel system, filter or pump. Not sure yet. Either way I am back to 18 mph on the highway.

On to 400k!

 

[CDW6212R]

Good to hear you found it and fixed it.